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69 lines
2.9 KiB
ArmAsm
69 lines
2.9 KiB
ArmAsm
ttl ieee format equivalent log (ieflog)
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***************************************
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* (c) copyright 1981 by motorola inc. *
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***************************************
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*************************************************
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* ieflog *
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* fast floating point logorithm *
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* *
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* input: d7 - ieee format input argument *
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* *
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* output: d7 - ieee format logorithmic result *
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* *
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* all other registers totally transparent *
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* *
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* condition codes: *
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* z - set if result is zero *
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* n - set if result is negative *
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* v - set if result is nan (not-a-number)*
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* (negative or nan argument) *
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* c - undefined *
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* x - undefined *
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* *
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* all other registers transparent *
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* *
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* maximum stack used: 54 bytes *
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* *
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* notes: *
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* 1) see the mc68344 user's guide for details*
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* concerning ieee format normalized range *
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* support limitations. *
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* 2) spot checks show relative errors bounded*
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* by 5 x 10**-8. *
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* 2) negative arguments are illegal and cause*
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* a nan (not-a-number) to be returned. *
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* 3) a zero argument returns minus infinity. *
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* *
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*************************************************
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page
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ieflog idnt 1,1 ieee format equivalent logorithm
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opt pcs
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section 9
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xdef ieflog entry point
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xref ffplog ffp logorithm routine
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xref iefsop front-end operand conversion routine
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xref ieftieee back-end convert to ieee and return
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xref iefrtnan back-end return nan routine
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xref iefrtod7 return original d7 from the caller
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xref ffpcpyrt copyright stub
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**************
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* log entry *
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**************
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ieflog jsr iefsop convert the operand
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bra.s iefnrm +0 branch normalized value
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* input argument is infinity +8
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bmi iefrtnan return a nan for a negative argument
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jmp iefrtod7 return plus infinity as the result
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* argument is normalized
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iefnrm bmi iefrtnan return a nan if argument is negative
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jsr ffplog call fast floating point log routine
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jmp ieftieee and return result in ieee format
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end
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